The overall objective of this research program are to determine the organization of neurons in the prevertebral ganglia, the origin, pattern and organization of synaptic input to neurons in the prevertebral ganglia and the occurrence of afferent synaptic input to these ganglia from different functional regions of the gastrointestinal tract. The areas of particular interest are: (1) to determine if "pacemaker-type" neurons are present in the cat inferior mesenteric and celiac ganglia and, if so, their location and distribution, (2) the pattern and organization of peripheral and central synaptic input to neurons in the cat inferior mesenteric ganglion, and (3) to determine if mechanoreceptors in the wall of the colon make synaptic contact with neurons in the inferior mesenteric ganglion of the cat. The method of approach will be the measurement in vitro of membrane properties and synaptic responses of single neurons using the intracellular recording technique.